Earth may be able to help cool itself, Yale study finds

Published 3:20 pm, Monday, July 25, 2016

NEW HAVEN >> The Earth may have some ability to reduce greenhouse gases in the atmosphere over long periods of time, a Yale University-led study has found.

The lowering of carbon dioxide is caused by its absorption into the planet’s rocky sediment, according to a release.

Today’s increase in CO2 most closely resembles an era 56 million years ago called the Paleocene-Eocene Thermal Maximum, in which an enormous amount of carbon was released into the atmosphere and ocean over the course of a few thousand years. The scientists found that sediment off the coast of Newfoundland demonstrates the PETM as well as absorption of CO2.

“It’s long been thought that when the planet warms, as it did during the PETM, the rate of rock weathering on land, which absorbs CO2 from the atmosphere, increases,” said Yale geologist Donald E. Penman, a postdoctoral fellow and first author of the paper published in the journal Nature Geoscience. “This draws down CO2 and cools the planet back down again.”

According to the Yale release, gradual weathering of rocks in the soil creates ions out of carbon dioxide that dissolve in the ocean. Plankton and coral then turn the ions into calcium carbonate, which settles into the ocean floor.

“What our paper details is a pulse of carbonate burial in the aftermath of the PETM,” Penman said in the release. “We analyzed a sediment core in which, before the PETM, there is no carbonate at all, and then in the recovery phase of the event, it has lots of carbonate.”

The area where Penman and his co-authors worked is known as the Newfoundland sediment drifts. Working aboard a ship known as JOIDES Resolution, they took core samples from the ocean floor as part of the Integrated Ocean Drilling Program, the release stated.

The scientists see the ancient absorption of carbon dioxide as an example of how the Earth keeps its atmospheric temperature in check, although the mechanism is extremely slow.

“We believe this process is going to operate in response to carbon emissions related to human activity,” Penman said. “But if the PETM is any guide, it will take tens of thousands of years.”